i have R830-13D, windows 7 x64 utlimate.
the "problem" is auto change lcd backlight depends of content of screen

for example - when i set brightness level to 2 and read some newsites (white background, black text) - it's ok for me. then, i open another website with black background and yellow text - lcd backlight changing down so i have to manually change it up by Fn+F7 to level 3.
and so on - when i change tab in browser to "normal" website - white background/black text - backlight automatically going up (looks like sequentially growing up by 3-4 little steps) and i have to decrease it back to level 2.

i can see this "issue" both for toshiba display driver (download on support page) and for intel display driver.